1. Field of the Invention
The present invention relates to a chromatography method and a chromatographic kit, in which a signal amplification operation is carried out in order to increase detection sensitivity.
2. Description of the Related Art
Among immunoassay methods, an immunochromatography method is generally used in many cases since it is easily handled and allows measurement to be performed in a short time. As an immune reaction used in an immunochromatography method, a competitive type reaction or a sandwich reaction is widely used. Between these, the sandwich reaction is mainly used in an immunochromatography method, and as a typical example thereof, the following operation is carried out to detect a test substance formed of an antigen in a sample. First, fine particles sensitized with antibodies to antigens which are test substances are immobilized to chromatographic carriers as fine solid phase particles, or the antibodies themselves are directly immobilized to the chromatographic carriers, whereby chromatographic carriers having reaction sites are prepared. Meanwhile, fine labeling particles are sensitized with antibodies which can bind specifically to the test substances, whereby sensitized fine labeling particles are prepared. These sensitized fine labeling particles and a sample move together on the chromatographic carriers in a chromatographic manner. By these operations, immobilized antibodies become an immobilization reagent in the reaction sites formed in the chromatographic carrier, and the sensitized fine labeling particles bind specifically to the antibodies via antigens which are test substances. Consequently, the presence or absence or the degree of the signals which are generated when the sensitized fine labeling particles are captured by the reaction sites is visually determined, whereby the presence or absence or the amount of the test substances included in the sample can be measured.
In the immunochromatography method, in order to avoid a problem (risk) that the antigen is not detected due to the low sensitivity, a method of amplifying detection signals is carried out in some cases. As the signal amplification method, an enzyme such as alkaline phosphatase and peroxidase is used as a label in some cases, or, detection is carried out by increasing the sensitivity by using a compound containing silver and a reductant for silver ions for a label selected from a group consisting of a metallic colloid label and a metallic sulfide label (silver amplification) in some cases. The immunochromatography method using such amplification is described in JP2002-202307A, JP2009-216695A, and JP2009-216696A, Journal of Chromatography, 878 (2010) 271-277, and the like.